U.S. Pat. No. 4,768,347, assigned to the assignee hereof, discloses a refrigerant recovery system that includes a compressor having an inlet coupled through an evaporator and through a solenoid valve to refrigeration equipment from which refrigerant is to be withdrawn, and an outlet coupled through a condenser to a refrigerant storage container or tank. The refrigerant storage container is carried by a scale having a limit switch coupled to control electronics to prevent or terminate further refrigerant recovery when the container is full. The scale comprises a platform pivotally mounted by a hinge pin to a wheeled cart, which also carries the evaporator/condenser unit, compressor, control electronics, and associated valves and hoses.
There is a need for refrigerant handling equipment, including refrigerant recovery equipment of the type disclosed in the above-noted U.S. Patent, that can handle differing types of refrigerants, such as R12, R22 and R502. A problem that is encountered lies in the fact that, following operation of the refrigerant recovery equipment, a significant amount of liquid refrigerant remains in the system. This refrigerant, which normally is located in the condenser, is sufficient to contaminant the next type of refrigerant to be recovered. It is therefore necessary to provide some mechanism for removing this refrigerant so as not to contaminate refrigerant subsequently recovered by the system.
U.S. Pat. No. 4,939,905, also assigned to the assignee hereof, discloses such a system, including a multiple-section condenser, and means responsive to refrigerant temperature and pressure at the outlet of the evaporator for automatically and selectively controlling flow of refrigerant from the compressor outlet to the individual condenser sections. Although this system is functional and efficient, it involves the expense of a multiple-section condenser, and is not as readily amenable as desired to retrofit in recovery equipment currently in the field.
It is therefore a general object of the present invention to provide a refrigerant handling system and method, particularly a refrigerant recovery system and method, that accommodate use in connection with multiple refrigerants of differing types while reducing or eliminating the possibility of refrigerant contamination through intermixing, that may be readily and economically implemented at the time of system manufacture or in equipment currently in the field, and that may be readily operated by relatively unskilled personnel.